The video analysis of an unbalanced fidget spinner

Abstract In this work, we propose an experiment with an unbalanced spinner, where one of its six arms (or lobes) was removed. The spinner was placed on a glass table on its body (base) in initial rotation. Its movement was filmed with a smartphone camera at 240 fps (720p HD), and the video was analyzed using the free Tracker software. The main results were (i) Showing that the rotation of the spinner no longer occurs around a fixed axis that passes through its center of mass (CM) but instead around a new axis, displaced in relation to the former main symmetry axis. (ii) Characterize the spinner’s movement on the table until it comes to rest for three points: its CM, the geometric center of its cylindrical body, and an arbitrary point on the arm opposite the removed one. (iii) Obtain an estimate of the magnitude of the maximum static friction coefficient between the glass and the spinner body surface.